Javaweb No hot deployment extension

Too long has not written something, today share a Java web of our simple dynamic load jar package, no need to hot deployment and update the previous class to go online Service application, Java's reflection mechanism content here do not do science (below the basic no code, only provide ideas, code Party bypass).

Environment: Java8+tomcat (the class plus in Tomcat is not the same as the loader of the javase, it is not considered);

Data interaction: WebService (JSON)

Idea: We all know that in general, Javaweb normal operation needs to be compiled into a class file to explain the operation, many times the system updates need to restart the service or service automatic hot deployment, regardless of the two modes, will make the session failure and some of the tasks are interrupted.

PHP is popular, not only the scripting language does not need to compile, and which module needs to update only need to update a file without the need to restart the service can be seamlessly updated. Based on this advantage, the idea is to use Java dynamic load mode + JSP script mode for project deployment, update, as far as possible to achieve code security.

When we create a web app, we need to update the class if there is a logic error inside the class, and the Web app needs to be restarted, but in fact, there are fewer opportunities to give you in a production environment, unless you can control the user for a period of time. Sometimes think that if you write a JSP script, it will appear that the code level is very low (as long as the security, fast, elegant, JSP is also a good choice), so every day until 12 o'clock late at night will not interrupt the system to update.

In fact, just load the jar file dynamically and update it regularly:

/* * to change this license header, choose license headers  In project properties. * to change this template file, choose  Tools | Templates * and open the template in the  editor. */package cn.skyatom.dynamicloader;import java.lang.reflect.method;import  java.net.url;import java.net.urlclassloader;import sun.misc.classloaderutil;/** *  Dynamic load Reflection mechanism loader  * *  @author  ZWK */public class Loader {     /**     *  Global Jar Pack Loader      */     private static java.util.map<string, urlclassloader> globjarloader =  new java.util.HashMap<String, URLClassLoader> ();    /**      *  get all the loaders &NBSP;&NBSP;&NBsp;  *  @return       */    public static  java.util.list<urlclassloader> getallclassloader ()  {         java.util.iterator<urlclassloader> lds = globjarloader.values (). Iterator ();         java.util.list<urlclassloader> list = new  java.util.ArrayList<URLClassLoader> (        while); Lds.hasnext ()) {&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;URLCLASSLOADER&NBSP;CL  = lds.next ();             list.add (CL);         }        return  list;    }    /**     *  implementing a method with parametric constructors      *     *  @param  jarid jar Bag id     * @ param clazname  Full class name      *  @param  methodname  Execution Method       *  @param  ctypes  constructor parameter types      *  @param   cvalues  constructor parameter values      *  @param  types  parameter Types       *  @param  values  parameter values      *  @return       *  @throws  java.lang.exception     */    public  static object excmethod (string jarid, string clazname, string  Methodname, class<?>[] ctypes, object[] cvalues, class<?>[] types,  object[] values)  throws Exception {         Urlclassloader loader =&nBsp;globjarloader.get (Jarid);        if  (loader == null )  {            return null;         }        Class<?>  Myclaz = loader.loadclass (clazname);         object c  = myclaz.getconstructor (ctypes). newinstance (cvalues);         method m = myclaz.getmethod (methodname, types);         object rs = m.invoke (c, values);         c = null;        return rs;     }    /**     *  methods for executing empty constructors       *     *  @param  jarid jar Package id     *  @param  clazname  full class name       *  @param  methodname  method names      *  @param  types  parameter Types      *  @param  values  parameter values       *  @return      */    public static object  excmethod (string jarid, string clazname, string methodname, class<?> [] types, object[] values)  throws Exception {         urlclassloader loader = globjarloader.get (Jarid);         if  (loader == null)  {             return null;        }         Class<?> myclaz = loader.loadclass (Clazname);         object c = myclaz.newinstance ();         method  m = myclaz.getmethod (methodname, types);         Object rs = m.invoke (c, values);         c =  null;        return rs;    }     /**     *  Execute static methods      *      *  @param  jarid jar bag id     *  @param   clazname  Full class name      *  @param  methodname  method name       *  @param  types  parameter types      *  @param  values  parameter values       * @return     */    public static object  Excstaticmethod (string jarid, string clazname, string methodname, class<?> [] types, object[] values)  throws Exception {         urlclassloader loader = globjarloader.get (Jarid);         if  (loader == null)  {             return null;        }         class<?> myclaz = loader.loadclass (Clazname);         method m = myclaz.getmethod (methodname, types);         object rs = m.invoke (null, values);         return rs;    }    /**     *  To execute a method with a parametric constructor      *     *  @param  obj  objects       *  @param  methodname  Execution Methods      *  @param  ctypes  constructor parameter types      *  @param  cvalues  constructor parameter values       *  @param  types  parameter types      *  @param  values   parameter values      *  @return      *  @throws   Java.lang.exception     */    public static object  excmethodbyobject (Bindclaz obj, string methodname, class<?>[] ctypes,  object[] cvalues, class<?>[] types, object[] values)  throws  Exception {        class<?> myclaz = obj.cclaz;         object c = obj.cobject;        method m  = myclaz.getmethod (methodname, types);         object  rs = m.invoke (c, values);        c =  null;        return rs;    }     /**     *  methods for executing empty constructors      *      *  @param  obj     *  @param  methodname  method name       *  @param  types  parameter types      *  @param   values  parameter values      *  @return      */     public static objEct excmethodbyobject (Bindclaz obj, string methodname, class<?>[] types,  object[] values)  throws Exception {         Class<?> myclaz = obj.cclaz;        object c  = obj.cObject;        Method m =  Myclaz.getmethod (methodname, types);         object rs =  m.invoke (c, values);        c = null;         return rs;    }    /**      *  Execute static method      *     * @ Param jarid jar Package id     *  @param  clazname  full class name       *  @param  methodname  method name      *  @param  types  parameter Types       *  @param  values  parameter values      *  @return       */    public static object excstaticmethodbyobject (BindClaz  obj, string methodname, class<?>[] types, object[] values)   throws exception {        class<?> myclaz =  obj.cclaz;        method m = myclaz.getmethod ( Methodname, types);         object rs = m.invoke ( null, values);         return rs;    }     /**     *  Create Objects      *      *  @param &Nbsp;jarid jar Package id     *  @param  clazname  full class name       *  @param  ctypes  parameter types      *  @param  cvalues  Parameter values      *  @return      */    public  static bindclaz createobject (string jarid, string clazname, class<?> [] ctypes, object[] cvalues)  throws Exception {         urlclassloader loader = globjarloader.get (Jarid);         if  (loader == null)  {             return null;        }         class<?> myclaz = loader.loadclass (Clazname);         if  (ctypes != null)  {             object c = myclaz.getconstructor (ctypes). newinstance (cvalues);             bindclaz bc = new bindclaz ();             bc.cClaz = myclaz;             bc.cObject = c;             return bc;         } else {            object  c = myclaz.newinstance ();             bindclaz bc = new bindclaz ();             bc.cClaz = myclaz;            bc.cobject = c ;            return bc;         }    }    /**      *  release all jar packages      */    public static void &NBSP;RELEASEALLJARPCK ()  {        if  (globjarloader ==  null)  {            return;         }        java.util.Iterator< String> jids = globjarloader.keyset (). Iterator ();         while  (Jids.hasnext ())  {             string jid =&nbsP;jids.next (); &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;RELEASEJARPCK (Jid);         }         Globjarloader.clear ();     }    /**     *   Release Package Resources      *     *  @param  jarid   &NBSP;&NBSP;&NBSP;*/&NBSP;&NBSP;&NBSP;&NBSP;PUBLIC&NBSP;STATIC&NBSP;VOID&NBSP;RELEASEJARPCK (String jarid)  {        if  (Globjarloader.get (Jarid)  != null)  {//            classloaderutil.releaseloader (Globjarloader.get (Jarid));//Release Loader              Globjarloader.remove (Jarid);        }    }     /**     *  loading      *     *  @param  jarid from Web protocol      *  @param  weburl     *  @throws   exception     */    public static void  Loadjarpckbyweb (String jarid, string weburl)  throws Exception {         if  (Globjarloader.get (Jarid)  != null)  {             classloaderutil.releaseloader (GlobJarLoader.get ( Jarid));//Release Loader         }         url jarurl = new java.net.url (Weburl);         urlclassloader myclassloader = new urlclassloader (new URL[]{jarurl},  Thread.CurrentThread (). Getcontextclassloader ()); &nbsP;       globjarloader.put (Jarid, myclassloader);     }    /**     *  Load Jar Package Resource      *      *  @param  jarid jar Bag id     *  @param  jarpath jar package file path      *  @throws  Exception     &NBSP;*/&NBSP;&NBSP;&NBSP;&NBSP;PUBLIC&NBSP;STATIC&NBSP;VOID&NBSP;LOADJARPCK (String jarid, String  jarpath)  throws Exception {        if  ( Globjarloader.get (Jarid)  != null)  {             classloaderutil.releaseloader (Globjarloader.get (Jarid));//Release Loader          }        URL jarurl = new  Java.io.File (Jarpath). Touri (). ToURL ();        urlclassloader myclassloader = new  URLClassLoader (New url[]{jarurl}, thread.currentthread (). Getcontextclassloader ());         globjarloader.put (Jarid, myclassloader);    }     /**     *  classes created by bindings      */     public static class BindClaz {         public object cobject = null;//objects created by reflection          public class<?> cclaz = null;//current class     }}

A simple dynamic load execution method, followed by a required code generator, will save development time and the corresponding operational efficiency:

The last generated code is put into the JSON file (JSP map), just fill in the corresponding parameters.

* * For Web applications, I wrote a timer in the app that regularly updates the latest version of the Jar expansion pack, and once there is an updated logic business, there is no need to restart the application or load (the load will have to be done sooner or later, if the condition permits).

I hope to give a little inspiration to the students who read here.

Redundant code also does not paste, based on the above thinking estimated to spend a few hours, you can also write a dynamic loading module about OK. Who says that Java cannot be developed as quickly as PHP, and that it can walk in a different way

Javaweb No hot deployment extension